Fatigue behavior and deformation mechanism of an as-cast Mg-Nd-Zr alloy tested at 150 °C

Abstract

Increasing testing temperature significantly decreases the tensile and fatigue strengths of the as-cast Mg-3.73Nd-0.56Zr alloy. The stress amplitude of the as-cast alloy tested at 150 °C remains basically unchanged until fatigue failure. The deformation behavior of the as-cast alloy at elevated temperature mainly depends on <a> and <c> or <c + a> dislocation-slip and twinning. The cracks of the as-cast alloy mainly originate from casting defects. The competition between micro-hardening and micro-softening determines the stress response behavior of the as-cast alloy during cyclic loading. The formation of dislocation walls and the interaction of the dislocations with the eutectic phase particles and twin boundaries result in work hardening. In contrast, the micro-softening is attributed to the shearing of the dislocations on the twins and the formation of the micro-cracks on the surface of the fatigued samples.